Sulfonation of polybenzoxazole and polybenzothiazole for improved adhesion to matrix resins

ABSTRACT

A method for sulfonating items comprising polybenzazole polymers is described. These sulfonated polybenzazole items are incorporated into composites containing a matrix resin such as an epoxy resin. The interfacial shear strength of these sulfonated polybenzazole fiber-containing composites is significantly improved over the interfacial shear strength of similar composites containing unsulfonated polybenzazole fibers.

BACKGROUND OF THE INVENTION

This invention relates to substituted polybenzazole polymers in variousphysical forms, such as fibers or films, and shaped articles such asmatrix composites and laminates containing these polybenzazole polymers.

Matrix composites, also known as fiber-reinforced composites, are shapedarticles comprising a plurality of fibers (the reinforcement) embeddedin a plastic (the matrix). Typically, the fibers give strength and/orstiffness to the composite, and the matrix maintains fiber alignment andtransfers load around broken fibers. The mechanical properties of thesematrix composites are known to depend upon how well the reinforcingfibers adhere to the matrix resin. Therefore, it is desirable tomaximize the adhesion between the fibers and the matrix resin.

Multilayer laminates are articles comprising multiple layers of filmsand other materials adhered together by various adhesives and/or othersealing techniques. Each layer in a laminate contributes a property,such as structural stability or moisture barrier, to the completedlaminate. For a laminate to function as designed it is important thatall of the layers of the laminate remain adhered to each otherthroughout the working life of the laminate. Therefore, it is desirableto maximize the adhesion between the layers of a multilayer laminate.

Matrix composites containing polybenzazole fibers have been prepared,and the use of polybenzazole films in multilayer laminates has beeninvestigated, therefore it would be desirable to improve the adhesion ofthe polybenzazole fibers to the matrix resin in a matrix composite andto improve the adhesion of the polybenzazole film to the other layers ina multilayer laminate.

SUMMARY OF THE INVENTION

The first aspect of this invention is a process to sulfonate fibers orfilms or other various items, containing polybenzoxazole and/orpolybenzothiazole. This process comprises contacting the fiber or filmor other item with a sulfonating agent, which is sulfur trioxide or anycompound which produees sulfur trioxide in situ.

The second aspect of this invention is the sulfonated polybenzoxazole orpolybenzothiazole polymer item itself.

The third aspect of this invention is a composite comprising:

(1) a sulfonated fiber of polybenzoxazole and/ or polybenzothiazole, and

(2) a matrix resin. The fourth aspect of this invention is a laminatecomprising:

(1) a sulfonated film of polybenzoxazole and/or polybenzothiazole, and

(2) other laminae, including at least one layer of

(2) a resin or adhesive.

The matrix composites which include sulfonated polybenzazole fibers haveincreased interfacial shear strength over those matrix composites madewith unsulfonated polybenzazole fibers. It is also believed thatsulfonated polybenzazole films would adhere better to the other layersof a multi-layer laminate than would an unsulfonated polybenzazole film.

DETAILED DESCRIPTION OF THE INVENTION

The present invention uses shaped articles containing polybenzazole(polybenzoxazole and polybenzothiazole) polymers. Polybenzoxazole,polybenzothiazole and random, sequential and block copolymers ofpolybenzoxazole and polybenzothiazole are described in references suchas Wolfe et al., Liquid Crystalline Polymer Compositions, Process andProducts. U.S. Patent 4,703,103 (October 27, 1987): Wolfe et al., LiquidCrystalline Polymer Compositions, Process and Products, U.S. Pat. No.4,533,692 (Aug. 6, 1985): Wolfe et al., Liquid CrystallinePoly(2,6-Benzothiazole) Compositions, Process and Products, U.S. Pat.No. 4,533,724 (Aug. 6, 1985): Wolfe, Liquid Crystalline PolymerCompositions. Process and Products. U.S. Pat. No. 4,533,693 (Aug. 6,1985): Evers, Thermoxadatively Stable Articulated p-Benzobisoxazole andp-Benzobisthiazole Polymers, U.S. Pat. No. 4,359,567 (Nov. 16, 1982):Tsai et al., Method for Making Heterocyclic Block Copolymer. U.S. Pat.No. 4,578,432 (Mar. 25, 1986): 11 Ency. Poly. Sci. & Eng.,Polybenzothiazoles and Polybenzoxazoles, 601 (J. Wiley & Sons 1988) andW. W. Adams et al., The Materials Science and Engineering of Rigid-RodPolymers (Materials Research Society 1989), which are incorporatedherein by reference.

The polymer may contain AB-mer units, as represented in Formula 1(a),and/or AA/BB-mer units, as represented in Formula 1(b) ##STR1## wherein:

Each Ar represents an aromatic group. The aromatic group may beheterocyclic, such as a pyridinylene group, but it is preferablycarbocyclic. The aromatic group may be a fused or unfused polycyclicsystem, but is preferably a single six-membered ring. Size is notcritical, but the aromatic group preferably contains no more than about18 carbon atoms, more preferably no more than about 12 carbon atoms andmost preferably no more than about 6 carbon atoms. Examples of suitablearomatic groups include phenylene moieties, tolylene moieties,biphenylene moieties and bis-phenylene ether moieties. Ar¹ in AA/BB-merunits is preferably a 1,2,4,5-phenylene moiety or an analog thereof. Arin AB-mer units is preferably a 1,3,4-phenylene moiety or an analogthereof.

Each Z is independently an oxygen or a sulfur atom.

Each DM is independently a bond or a divalent organic moiety that doesnot interfere with the synthesis, fabrication or use of the polymer. Thedivalent organic moiety may contain an aliphatic group, which preferablyhas no more than about 12 carbon atoms, but the divalent organic moietyis preferably an aromatic group (Ar) as previously described. It is mostpreferably a 1,4-phenylene moiety or an analog thereof.

The nitrogen atom and the Z moiety in each azole ring are bonded toadjacent carbon atoms in the aromatic group, such that a five-memberedazole ring fused with the aromatic group is formed.

The azole rings in AA/BB-mer units may be in cis- or trans-position withrespect to each other, as illustrated in 11 Ency. Poly. Sci. & Eng.,supra. at 602, which is incorporated herein b reference.

The polymer preferably consists essentially of either AB-polybenzazolemer units or AA/BB-polybenzazole mer units, and more preferably consistsessentially of AA/BB-polybenzazole mer units. The molecular structure ofthe polybenzazole polymer may be rigid rod, semi-rigid rod or flexiblecoil. It is preferably rigid rod the case of an AA/BB-polybenzazolepolymer or semi-rigid in the case of an AB-polybenzazole polymer. Azolerings within the polymer are preferably oxazole rings (Z =0). Preferredmer units are illustrated in Formulae 2 (a)-(h) The polymer morepreferably consists essentially of mer units selected from thoseillustrated in 2(a)-(h), and most preferably consists essentially of anumber of identical units selected from those illustrated in 2(a)-(c).##STR2##

Each polymer preferably contains on average at least about 25 mer units,more preferably at least about 50 mer units and most preferably at leastabout 100 mer units. The inherent viscosity of rigid AA/BB-polybenzazolepolymers in methanesulfonic acid at 25° C. is preferably at least about10 deciliters/gram ("dL/g"), more preferably at least about 15 dL/g, andmost preferably at least about 20 dL/g. For some purposes, an inherentviscosity of at least about 25 dL/g or 30 dL/g may be best. Inherentviscosity of 60 dL/g or higher is possible, but the inherent viscosityis preferably no more than about 40 dL/g. The inherent viscosity ofsemi-rigid AB-polybenzazole polymers is preferably at least about 5dL/g, more preferably at least about 10 dL/g and most preferably atleast about 15 dL/g.

The polymer is fabricated into fibers and films by spinning or extrudingfrom a dope. If freshly made polymer or copolymer is not available forspinning or extruding, then previously made polymer or copolymer can bedissolved in a solvent to form a solution or dope. Some polybenzoxazoleand polybenzothiazole polymers are soluble in cresol, but the solvent ispreferably an acid capable of dissolving the polymer. The acid ispreferably non-oxidizing. Examples of suitable acids includepolyphosphoric acid, methanesulfonic acid and sulfuric acid and mixturesof those acids. The acid is preferably polyphosphoric acid and/ormethanesulfonic acid, and is more preferably polyphosphoric acid.

The dope should contain a high enough concentration of polymer for thepolymer to coagulate to form a solid article but not such a highconcentration that the viscosity of the dope is unmanageable to handle.When the polymer is rigid or semi-rigid, then the concentration ofpolymer in the dope is preferably high enough to provide a liquidcrystalline dope. The concentration of the polymer is preferably atleast about 7 weight percent, more preferably at least about 10 weightpercent and most preferably at least about 14 weight percent. Themaximum concentration is limited primarily by practical factors, such aspolymer solubility and, as already described, dope viscosity. Because ofthese limiting factors, the concentration of polymer is seldom more than30 weight percent, and usually no more than about 20 weight percent.

Suitable polymers or copolymers and dopes can be synthesized by knownprocedures, such as those described in Wolfe et al., U.S. Pat. No.4,533,693 (Aug. 6, 1985): Sybert et al., U.S. Pat. No. 4,772,678 (Sep.20, 1988): Harris, U.S. Pat. No. 4,847,350 (July 11, 1989): andLedbetter et al., "An Integrated Laboratory Process for Preparing RigidRod Fibers from the Monomers," The Materials Science and Engineering ofRigid-Rod Polymers at 253-64 (Materials Res. Soc. 1989), which areincorporated herein by reference. In summary, suitable monomers(AA-monomers and BB-monomers or AB-monomers) are reacted in a solutionof nonoxidizing and dehydrating acid under nonoxidizing atmosphere withvigorous mixing and high shear at a temperature that is increased instep-wise or ramped fashion from a starting temperature of no more thanabout 120° C. to a final temperature of at least about 190° C. Examplesof suitable AA-monomers include terephthalic acid and analogs thereof.Examples of suitable BB-monomers include 4,6-diaminoresorcinol,2,5-diaminohydroquinone, 2,5-diamino-1,4-dithiobenzene and analogsthereof, typically stored as acid salts. Examples of suitableAB-monomers include 3-amino-4-hydroxybenzoic acid,3-hydroxy-4-aminobenzoic acid, 3-amino-4-thiobenzoic acid,3-thio-4-aminobenzoic acid and analogs thereof, typically stored as acidsalts.

B. Shape Formation

Acid dopes of polybenzazole polymers are coagulated to form varioususeful items.

1. Fiber

A fiber can be formed by dry-jet wet spinning the polybenzazoledope. Inthis method, conventional equipment is used to extrude the fiber throughan air gap into a coagulating bath. The extrudate is then stretched bywinding the fiber at a linear speed greater than the speed at which itleaves the spinneret jet. The spin-draw ratio can be as high as 20:1.The technique for spinning such a fiber is well-known and is describedin such references as U.S. Pat. Nos. 4,263,245 and 4,606,875 and inChenevey, "Formation and Properties of Fiber and Film from PBZT," TheMaterials Science and Engineering of Rigid-Rod Polymers p. 245(Materials Research Society 1988).

2. Film

Films are formed by a known process involving extrusion of polybenzazoledope through a die, and then through a variable air-gap length into thecoagulating bath. The extrusion process may, for example, run through aflat die onto a rotating drum or through a counter rotating die. Thepolymer dope may be stretched before coagulation to provide mono- orbiaxial orientation. Processes for synthesizing films are described inthe following references: U.S. Pat. Nos. 4,051,108: 4,487,735; and4,898,924, and PCT publications WO 89/12072, WO 89/12546 and WO89/12547, which are incorporated herein by reference. Once created, thefilms may then be heat-treated under tension to increase their strength.Conventional equipment and techniques are used for this procedure.

C. Sulfonation

Various items of polybenzazole (polybenz-othiazole or polybenzoxazole)polymers can be sulfonated by contact with a sulfonating agent. Thisprocess comprises contacting the article with a sulfonating agent whichis sulfur trioxide ("S03") or any compound which produces sulfurtrioxide in situ. It is also known that SO₃ can be complexed withcertain Lewis bases, and there are certain organic compounds whichrelease SO₃.

There are two methods of contacting the polybenzazole polymer with asulfonating agent. The first is to immerse the polybenzazole polymer ina liquid which contains a sulfonating agent. The second method is toexpose the polybenzazole polymer to a gaseous environment which containsa gaseous sulfonating agent.

A means of contacting the polybenzazole polymer with a liquidsulfonating agent is to expose it to a solution of sulfur trioxide (SO₃)in a halocarbon solvent that dissolves the SO₃ and causes thepolybenzazole polymer to slightly swell without dissolving thepolybenzazole polymer. The solvent is preferably a chlorofluorocarbonsolvent, such as 1,1,2-trichloro-1,2,2-trifluoroethane (sold under thetrademark Freon 113®). This solvent is preferred because the1,1,2-trichloro-1,2,2-trifluoroethane causes the polybenzazole polymerto slightly swell, which allows for better penetration of the article bythe SO₃. The 1,1,2-trichloro-1,2,2-trifluoroethane also reduces thereactivity of SO₃ so there is much less chance that the SO₃ will reactso extensively with the polybenzazole polymer as to cause oxidativedegradation of the polymer.

The sulfonation process begins when an item, such as a fiber or film,made of polybenzazole is placed in contact with one of the sulfonatingagents previously described. The optimal conditions of sulfonation willvary, depending on the polybenzazole polymer and whatever sulfonatingagent is used. The optimal temperature for sulfonation is between 5° C.and20O° C. with a preferable range of between 20° C. and 30° C. and themost preferred temperature being ambient room temperature of about 25°C.

In a method of sulfonating the polybenzazole polymer by means of aliquid sulfonating agent, it is effective to use a solution of sulfurtrioxide in a liquid that also swells the said polymer. One example ofsuch a "swelling liquid" is the previously described chlorofluorocarbonsolvent, trichlorotriflouroethane. The concentration of sulfur trioxidein the solvent can range from about 0.1 percent to about 25 percent byweight, with a preferred concentration being about 8 percent by weight.A conventional bath, as known to be used in liquid sulfonationprocesses, is used to make contact between the sulfonating agent,swelling compound, and the polybenzoxazole or polybenzothiazole polymer.It is, of course, to be understood that the swelling step and thesulfonation step do not have to be simultaneous as this methoddescribes.

In a liquid medium, the polybenzazole polymer is maintained in contactwith the sulfonating agent for a time within the range of 10 seconds to5 minutes. The preferred contacting time for sulfonating in a liquidmedium is about 20 seconds. The sulfonation reaction is essentiallyinstantaneous, however, a longer reaction time increases the sulfonatingagent's ability to penetrate the polybenzazole polymer. If the reactionis allowed to proceed longer than the recommended time, then undesirableoxidative degradation of the polymer may take place. Oxidativedegradation of the sulfonated polybenzazole polymer is apparent if thearticle swells and takes on a gelatinous appearance when it is immersedin water.

A method of sulfonating the polybenzazole polymer with a gaseoussulfonating agent is to expose the article to gaseous sulfur trioxide.The gaseous sulfur trioxide is preferably diluted with a dry inertcarrier gas such as air, nitrogen, helium, carbon dioxide, sulfurdioxide and the like. When gaseous sulfur trioxide is used as thesulfonating medium, the concentration of the sulfur trioxide in theinert gas should be less than or equal to 20% in order to minimize theheat of reaction. The amount of time required to sulfonate apolybenzazole polymer by using a gaseous sulfonating agent ranges frombetween about .02 seconds to about 5 hours.

To expose a polybenzazole polymer to a gaseous sulfonating agentinvolves running a continuous polybenzazole fiber spinning line or filmextruding line through a device in which there is a gaseous sulfonatingagent present, along with an inert dilution gas. The advantages of usinga gaseous sulfonating system include faster reaction times (as little as0.02 seconds may be required to sulfonate in a gaseous sulfonatingmedium) and the nonexistence of liquid halocarbon solvent waste to dealwith.

U.S. Pat. No's. 4,663,142: 4,673,560 and 4,915,912 disclose apparatisuitable for gaseous sulfonation of various materials. These patents areincorporated herein by reference.

In both the liquid and gaseous sulfonation processes, after contact withthe sulfonating agent the sulfonated surface of the polybenzazolepolymer preferably should be neutralized. This is accomplished bycontacting the sulfonated surface or surfaces with a neutralizing agent.Any neutralizing agent capable of neutralizing the sulfonic acid groupsof the sulfonated surface is suitable for the purposes of thisinvention. Advantageous neutralizing agents include dilute aqueoussolutions of alkali metal hydroxides or salts thereof and a weak acid:alkaline earth metal hydroxides or salts thereof and a weak acid: heavymetal chlorides or sulfates, primary, secondary or tertiary amines:quaternary ammonium salts: ammonia gas and ammonium hydroxide: andmixtures thereof. Neutralization can be effected by contacting thesulfonated surfaces with the foregoing aqueous solutions or suspensionssuch as by dipping, spraying or wiping the polybenzazole polymer withthe solutions, washing with water and then drying the polymer.

Contact time and sulfonating agent concentration for the sulfonationreaction are inversely related. This means that shorter reaction timesare required for higher sulfonating agent concentrations and longerreaction times are required for weaker sulfonating agent concentrations.Therefore, a wide range of sulfonating agent concentrations are usablewith this invention and the degree of sulfonation imparted can becontrolled with exposure time.

The changes in the polybenzazole article brought about by thesulfonation procedure depend upon the degree of exposure the articleexperiences. Mild or short exposure is believed to cause a reactionbetween the SO₃ and only the weak outer layers of polybenzazole. Longerexposure is believed to allow deep penetration and the attachment ofmany sulfonate groups. Prolonged exposure will degrade thepolybenzazole. Therefore, the sulfur content of the polybenzazolepolymer after sulfonation will range from being barely detectable tobeing possibly as high as 3 percent of the polymer on a weight basis.

D. Utility of Sulfonated Polybenzoxazole and/or PolybenzothiazolePolymers in Various Physical Forms

1) Composites

The sulfonated polybenzazole polymers obtained from this invention canbe used to reinforce a variety of thermosetting and thermoplasticpolymer matrix materials. Epoxy resin is the preferred matrix materialfor these composite applications but unsaturated polyesters,polyurethanes, polycyanates, rubbers, polyamides, and polyesters canalso be used. The resulting matrix composite, reinforced with sulfonatedpolybenzoxazole or polybenzothiazole polymers in fiber form, preferablyattains a higher interfacial shear strength than do composites made withunsulfonated fibers. The improvement in interfacial shear strengthattained is preferably at least 25 percent, more preferably at least 50percent, and most preferably at least 75 percent. These reinforcedcomposites find application for use as structural members in structuresrequiring a high ratio of strength to weight such as are required intransportation vehicles or equipment.

2) Enhanced Polarity

The sulfonate functionality adds polarity to polybenzoxazole orpolybenzothiazole, and in so doing, adds polar stability for thepolymer's ion related uses. An attached sulfonate group adds an anionicsite. The sulfonated polybenzoxazole or polybenzothiazole iselectrically conductive and will conduct a static charge. Additionally,the anionic site offers a change in the surface tension characteristicfrom unsulfonated polybenzoxazole and polybenzothiazole. Because of thischange of surface tension characteristic, when sulfonatedpolybenzoxazole or polybenzothiazole is mixed with an ionic medium likea latex, a more stable mixture can be obtained over that which can beobtained using unsulfonated polybenzoxazole or polybenzothiazole. Also,because of this change in surface tension characteristic, the sulfonatedpolymer has greater wettability. Therefore, a highly polar solvent, likewater, is more easily retained on the surface of the sulfonated polymer.

Illustrative Embodiment

The following example is given to illustrate the invention and shouldnot be interpreted as limiting it in any way. Unless stated otherwise,all parts and percentages are given by weight.

EXAMPLE

Polybenzoxazole is sulfonated by sulfur trioxide by adding 0.477 gramsof polybenzoxazole fibers to a 4.0 ounce bottle containing a solution of0.8 percent sulfur trioxide in 1,1,2-trichloro-1,2,2-trifluoroethane.The fibers are allowed to react for 20 seconds and then the solution isdrained off. After draining off the sulfur trioxide solution the fibersare washed with 2.0 percent ammonia in water to neutralize the sample.After this neutralization, the fibers are washed twice with fresh waterand then allowed to dry. The sulfur content of this sulfonatedpolybenzoxazole is approximately 0.08 percent by weight.

A composite is made containing the so-treated fibers. Twenty-two (22.0)grams of Tactix 123® epoxy resin (an epoxy resin with an epoxyequivalent weight of 173, sold by The Dow Chemical Company), are placedin a 50 ml beaker. Three and forty four hundredths (3.44) grams ofmeta-phenylene diamine, equivalent weight of 27.04 grams, is placed in asecond 50 ml beaker. Both beakers are placed in an air oven and heatedto 70° C. The two materials are then combined by first pouring themeta-phenylene diamine into the epoxy and then stirring well. Thismixture is then poured into the beaker containing the residualmetaphenylene diamine and stirred. The mixture is degassed in a vacuumoven at 70° C.

Next, the sulfonated polybenzoxazole fibers are placed evenly in amulti-cavity dog-bone mold. The mold containing the fibers is placed ina vacuum oven at 70° C. for 30 minutes. When the epoxy resin reaches 70°C. in temperature, the epoxy resin mixture is poured into the moldcontaining the fibers. The mold is then placed in an air oven, and theepoxy resin is cured at 75° C. for two hours, then the oven temperatureis increased to 125° C. for two hours. After this, the oven is turnedoff and the coupon is allowed to cool to room temperature. Then thecured epoxy resin containing the polybenzoxazole is removed from themold. By following this procedure, coupons containing sulfonatedpolybenzoxazole fibers reinforcing an epoxy resin are obtained.

As stated previously the interfacial shear strength of the fibercontaining composite matrix can be tested by an "embedded singlefilament shear strength method" as described in Drzal et al., Adhesionof Graphite Fibers to Epoxv Matrixes: I. The Role of Fiber SurfaceTreatment, 16 J. Adhesion 1-30 (1982).

This method is briefly described as follows: a single fiber is axiallyaligned and embedded in a polymeric matrix dog-bone coupon. The couponis incrementally strained causing the embedded fiber to fracture intosmaller and smaller fragments. Strain is increased until no more fiberfracture occurs. From analysis of the fiber fragment lengths, fiberdiameter, and fiber tensile strength the interfacial shear strength canbe calculated.

The coupons prepared by the above-described method have an interfacialshear strength of above 17.9 Mpa (2,593 psi). Coupons similarly preparedand tested but containing unsulfonated polybenzoxazole fibers have aninterfacial shear strength of 10.1 MPa(1,466 psi). Thus, surfacesulfonation of the polybenzoxazole fibers used in a matrix composite hasbeen shown to increase the interfacial shear strength of the compositeby 74%.

What is claimed is:
 1. A sulfonated polybenzazole polymer or copolymer.2. The polymer or copolymer of claim 1 wherein said sulfonatedpolybenzazole polymer or copolymer is sulfonated cis-polybenzoxazole. 3.The polymer or copolymer of claim 1 wherein said sulfonatedpolybenzazole polymer or copolymer is sulfonated AB-polybenzoxazole. 4.The polymer or copolymer of claim 1 wherein said sulfonatedpolybenzazole polymer or copolymer is sulfonated polybenzothiazole. 5.The polymer or copolymer of claim 1 wherein said sulfonatedpolybenzazole polymer or copolymer is sulfonatedtrans-polybenzothiazole.
 6. The polymer or copolymer of claim 1, whichis in the form of a fiber.
 7. The polymer or copolymer of claim 1, whichis in the form of a film.
 8. A process for sulfonating an item ofpolybenzazole comprising the step of contacting said item with asulfonating agent which is sulfur trioxide or any compound whichproduces sulfur trioxide in situ under conditions such that said itemexhibits measurably improved adhesive properties as measured bydetermining the interfacial shear strength of composites or laminatescontaining said item.
 9. The process of claim 8 wherein said sulfonatingagent is sulfur trioxide.
 10. The process of claim 8 wherein saidsulfonating agent comprises a mixture of gaseous sulfur trioxide in adry, inert carrier gas.
 11. The process of claim 10 wherein said mixtureof gaseous sulfur trioxide in an inert carrier gas contains 20 percentor less sulfur trioxide.
 12. The process of claim 11 wherein saidsulfonating agent contacts said item of polybenzazole for between about0.02 seconds to about 5 hours at a temperature between about 5° C. toabout 100° C.
 13. The process of claim 8 wherein said sulfonating agentcomprises a mixture of sulfur trioxide in a liquid halocarbon solvent.14. The process of claim 13 wherein said liquid halocarbon solvent is achlorofluorocarbon solvent.
 15. The process of claim 14 wherein saidliquid halocarbon solvent is 1,1,2-trichloro-1,2,2-trifluoroethane. 16.The process of claim 15 wherein said item is contacted with saidsulfonating agent at a temperature of between about 5° C. to about 100°C. for between about 10 seconds to about 5 minutes.
 17. The process ofclaim 15 wherein said item is contacted with said sulfonating agent at atemperature of about 10° C. to about 30° C. for between about 10 secondsto about 2 minutes.
 18. The process of claim 15 wherein said item iscontacted with said sulfonating agent at a temperature of about 25° C.19. The process of claim 15 wherein said item is contacted with saidsulfonating agent for about 20 seconds.